Chronic sinusitis is a disease in which a natural orifice is closed due to the swelling of the mucous membrane by inflammation of paranasal sinuses and the storage of mucus in the sinus or generation of polypoid tissues (nasal polyps) in the nasal cavity occurs, thereby causing clinical symptoms such as nasal discharge, nasal obstruction, postnasal drip, and dull headache. Chronic sinusitis is caused by various factors, and it is considered that this disease is influenced by bacterial or viral infection, allergic reaction, genetic factors, living environment, etc. Methods for treating chronic sinusitis include administration of antibiotics and various types of surgical treatments.
Allergic rhinitis caused by various types of allergic reactions has symptoms similar to those of chronic sinusitis. Thus, it is difficult to distinguish allergic rhinitis from chronic sinusitis based on subjective findings. Since administration of antiallergic agents is effective for the treatment of allergic rhinitis, it is desirable to easily distinguish the two diseases and to perform suitable treatments on both of them.
However, to date, endoscopy or radiographic examination has been generally performed on tissues in the nasal cavity as a method for diagnosing chronic sinusitis. Since these diagnostic methods have required examination and evaluation performed by medical specialists, these methods have not necessarily been simple, and great burdens have been placed on patients.
Recently, chronic sinusitis has also been diagnosed by observing surgical specimens or nasal polyp tissues in inflammatory sites under a microscope. This diagnostic method utilizes the phenomenon in which inflammation-related substances generated as a result of infiltration of neutrophils, eosinophils and the like, such as cytokines, growth factors, adhesion molecules, and inflammatory substances, are increased in the inflammatory sites of chronic sinusitis. This method makes a diagnosis of chronic sinusitis based on the presence or absence of these substances, or the density of these substances. For instance, Patent Literature 1 discloses a method for diagnosing the severity of chronic sinusitis by measuring the expression of a hematopoietic prostaglandin D synthase (H-PDGS) protein or the amount of prostaglandin D2 (PDG2) in inflammatory sites based on tissue observation. The present inventors have also studied the expression of pendrin and periostin proteins in surgical specimens, and as a result, they have reported that it is possible to distinguish chronic sinusitis from allergic rhinitis based on an increase in the expression of pendrin and periostin in the inflammatory sites of chronic sinusitis or allergic rhinitis, so as to make a diagnosis (Non Patent Literature 1).
However, the aforementioned diagnosis, which uses an inflammation-related substance in a surgical specimen or the like as a marker, is also attended with complications such as limited facilities in which the diagnosis can be carried out, the long period of time required for obtaining results, invasiveness for patients upon collection of nasal tissues and the like. Thus, it has been desired to develop a novel tool, which improves the accuracy of diagnoses by medical specialists according to a more simple method, and which also enables the accurate diagnosis of chronic sinusitis even by non-specialists.